void fast9_detect(struct image_t *img, uint8_t threshold, uint16_t min_dist, uint16_t x_padding, uint16_t y_padding, uint16_t *num_corners, uint16_t *ret_corners_length, struct point_t **ret_corners, uint16_t *roi)
Do a FAST9 corner detection.
int fast9_detect_pixel(struct image_t *img, uint8_t threshold, uint16_t x, uint16_t y)
Do a FAST9 corner detection for a single pixel.